Preparation of Poly(diiododiacetylene), an Ordered Conjugated Polymer of Carbon and Iodine

Abstract

Conjugated organic polymers generally must include large substituents for stability, either contained within or appended to the polymer chain. In polydiacetylenes, the substituents fulfill another important role: During topochemical polymerization, they control the spacing between the diyne monomers to produce an ordered polymer. By using a co-crystal scaffolding, we have prepared poly(diiododiacetylene), or PIDA, a nearly unadorned carbon chain substituted with only single-atom iodine side groups. The monomer, diiodobutadiyne, forms co-crystals with bis(nitrile) oxalamides, aligned by hydrogen bonds between oxalamide groups and weak Lewis acid-base interactions between nitriles and iodoalkynes. In co-crystals with one oxalamide host, the diyne undergoes spontaneous topochemical polymerization to form PIDA. The structure of the dark blue crystals, which look copper-colored under reflected light, has been confirmed by single-crystal x-ray diffraction, ultraviolet-visible absorption spectroscopy, and scanning electron microscopy.

Molecular Assemblies from Imidazolyl‐Containing Haloalkenes and Haloalkynes: Competition between Halogen and Hydrogen Bonding

“…In addition, this study provides valuable information that can be used to organize suitably diacetylenic molecules for solid-state polymerization, as demonstrated recently by Goroff and co-workers. [40] We also report that these molecules are capable of forming cocrystals with other organic modules that possess hydrogen-bonding capabilities, as testified by the X-ray crystal structure of 4. In this case, the N···I halogen-bonding scheme observed in 5 is disrupted because the imidazolyl group, the most basic moiety in the molecule, is part of the hydrogen-bonding network.…”

“…This "tour de force" was accomplished by forming halogenbonded complexes between diiododiacetylene and oxalamide-containing hosts terminated with nitrile groups at both ends. [40] In these host-guest complexes, the diacetylenic guest is suitably oriented for topochemical polymerization. Previous attempts to do the same using host molecules with pyridyl groups instead of nitrile groups had been unsuccessful as a result of steric problems.…”

Halogen Bonding in Crystal Engineering

“…Optimizing the electrostatic and charge transfer aspects have been successfully used in designing of drugs, liquid crystals, organic semiconductors, magnetic materials, nonlinear optical materials, and templates for solid synthesis. [12][13][14][15][16] Conventionally, halogen bonds have been divided into two classes, TypeI and Type II (Fig. 3), based solely on the bonding geometry.…”

Molecules in the Solid State

“…13,14 Others have built on Schmidt's strategy of topochemical solid-state reactions to make polydiacetylenes-potentially useful as optical limiters, waveguides, and thermometric sensors-directly from crystals of discrete diacetylene molecules that are aligned properly in the solid state. [15][16][17] New materials based on infinite frameworks, bounded only by their crystal dimensions, constructed from molecular "tinkertoys" held together by hydrogen bonding or metal-ligand coordination are emerging as promising candidates for molecular separations and gas storage. 18,19 More recently, the materials science of pharmaceutical compounds, which often consist of small-molecule crystals, has attracted considerable attention, owing to the importance of crystal form (i.e., polymorphs), phase stability, and mechanical properties in therapeutic formulations.…”